Listening helmet for sound locators



May 20, 1941. I F. R. HOUSE LISTENING HELMET FOR sounn LOCATORS Filed July 29, 1939 2 Sheets-Sheet 1 May 20, 1941. F. R. HOUSE LISTENING HELMET FOR SOUND LOCATORS 2 Sheets-Sheet 2 Filed Jl lly 29, 1939 INVENTOR Jam/r Patented 2,242,953 LISTENING HELMET FOR SOUND LOCATORS Frank House, Baldwin Harbor, N. Y., assignor to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application Italy 29, 1939, Serial No. 287,236 3 Claims. (01. 181-26) This invention relates, generally, to apparatus for locating aircraft or other moving targets under conditions of poor visibility, as at night or during fog, and the invention has reference, more particularly, to improvements in sound locator 'receivers and associated apparatus of the type of an aircraft or other object to be located cannot be made audible until its'total sound level at the listening station or some part of its'sound spectrum reaches a'level approximating that of the ambient. A reduction in ambient sound results in increased listening range, and hence soundproofing of sound locator receivers to reduce ambient sound in the receiver is important. Ambient sound maybe divided into two classes, 1. e., general background and local noises, the first consisting of sound that is generated at a distance from the receiver and is air borne to the latter, and the second consisting of sound generated within the receiver assembly and transmitted directly by vibration to the receiver sound track.

The present invention is a continuation in part of my prior application, now Patent No. 2,199,404,

Fig. 3 is a section through the helmet, on an enlarged scale, taken approximately on line 33 of Fig. 2.

Fig. 4 is a front elevation of one of the metal plates of the helmet which surrounds each ear.

Fig. 5 is a transverse section taken approximatelyon broken'line 5-5 of Fig. 4.

'Fig; 6 is a side elevation of one of the adjustable ear pieces or tubes of the helmet.

Referring now to the said drawings, the sound locator apparatus comprises a suitable arrangement of'listening or sound collecting receivers or horns I, 2 and 3 mounted for both turning in azimuth and tilting in elevation, the horn 2 being a common horn in that it cooperates with horn! in making elevation determinations and with'horn 3 in making azimuth determinations. The horns or receivers I, 2,3 are carried by arms: 6, 5, 6 that are detachably secured toa common crossshaft 8 which is, in turn, mounted for turning in elevation on a head I by means of an elevation handwheel 9 connected through gearing for Sound Locator Apparatus, dated May '7, 1940,

and pertains particularly to the listening helmets.

worn by the listeners who operate' the sound locator. The helmets are especially designed to exclude all background noises from the ears of the listener so that only the sound arriving through the tubes connected with the sound 10- cators is heard by the listener. To this end, metal plates are provided around eachear piece to support the transmitting tubes and to fit the head tightly around the ear so as to exclude outside 1 noises. The metal plate is padded on both sides with soft pliable material of the helmet, such as soft leather or rawhide, and an annular padded portion placed between the head and the metal plate around the ear. Further objects and advantages will become apparent from the following specification.

Referring to the drawings, showing the preferred form of my invention,

.Fig. l is a perspective view, in elevation, takgn from the rear of the complete sound locating apparatus.

Fig. 2 is a side elevation of the helmet as worn by a'listener, with the same disconnected from the tubes normally connecting it to the listening horns.

ID for turning the horns l, 2, 3. Head 1 contains the sound lag correction and other apparatus forming no part of the present invention, and is mounted for turning in azimuth on a pedestal 8 by means of an azimuthhandwheel (not shown) Pedestal 8 is mounted upon a circular platform l2 that'is supported in a level position by adjustable leveling screws l3.' t a Forleading the sound received from the horns to the listeners ears, I preferably employ icomplete helmets It and I5 for the train operator and the elevation operator, respectively, the former being shown as connected through tubes "5 and IT to the horns 2 and 3 and the helmet l5 being shown as connected through tubes land Hi to the horns I and 2. Said tubes are of soft rubber so as not to transmit vibrations to the helmets. Each helmet is preferably made of leather and is strapped'on the head by several cross straps 20: 2| and 22 and by a chin strap 23,

said straps extending between pieces of rawhide 24 secured to the helmet around each ear piece.

The ear pieces are mounted in the sides of the helmet, so that the helmet may be adjusted by means of the straps to accurately position the ear pieces and hold them comfortably in place.

The ear piece structure is shown in section in Fig. 3 and comprises a plate 25 of sheet material, such as aluminum, of a generally elliptical contour, as shown in Fig. 4, but dished or cuppedso that the outer edge fits the contour of the head a or skull around the ear,-while sufiicient space is allowed in the middle for the ear. Fi 3 shows a cross section of the plate in the vertical plane, while Fig. 5 shows a transverse section. This plate is provided with a central hollow boss or extension 26 which is threaded interiorly for a short distance, as at 21. Into said threaded portion is screwed the ear piece proper 28 shown in elevation in- Fig. '6. metallic portion 29 having an outer knurled collar 30 and provided with threads 3| to screw into the aforesaid threads 21. On its forward end I provide a short tube or thimble 32, preferably made of plastic or insulating material, such as Bakelite or rubber, and provided with a rounded end 33 which is designed to fit into the concha of the ear. The inner diameter of this tube is kept substantially unrestricted so as to impose no baffling or attenuating effect in thesound track. In order to fit into the concha of the ear, the diameter is also made materially less than the diameter of the ordinary ear piece of a telephone receiver which fits over the outer ear, j

This comprises a short central apertures of tubes 29 and shifts these tubes 29, and hence the ear pieces of the helmet, if necessary, so as to align the tubes with the ear conchas. He thereupon turns the conduits or tubes 29 so as to thread these tubes inwardly or outwardly to bring the ear pieces 32 into comfortable position within the ear conchas. when he desires to listen in at the apparatus, it is order of an inch have been found satisfactory for 1 this purpose. A sound locator helmet must be worn for long periods of time and must therefore be comfortable to the wearer, and ear pieces of the type which fit into the auditory canal not only become extremely uncomfortable after short v wear, but also the sound track passage theremaximum reception. Likewise, the larger ear pieces similar to a telephone receiveralso become uncomfortable and, in addition, do not exclude extraneous, noises eil'ectively. By screwing the 'member 29 in and out, it may be brought into comfortable engagement "with the ear so as-to further exclude outside noises. The interior of through is so restricted as to interfere-with the the tube 29 may be provided with aspring ring 34 to detachably hold in place a connecting tube or fitting 35 on the end of one of the rubber tubes l6. Hence the user may fit the helmet on the head irrthe desired position-before connecting the tubes leading to the sound locators, and then when the helmet is fitted to his taste,fit-. tings 35 may be inserted into the tubes 29 on each side of the helmet and held in place by the springs 34 with their inner 31 within tubes 23.

An'elliptical pad 36 is'stitched r otherwise secured to the helmet around the edge of each ends against collar plate 25 t0 fit tightly against the head. This the head and plate is also a valuable aid toward this end. I

In using the helmet, the operator places the same upon his head with the tubes 19 and i1 disconnected and inserts his forefingers into the the diameter of the ear concha, said tube being adjustably movable in said plate aperture toward a merely necessary to plug the nipple plugs 35 of the tubes IS, IT, or l8, l9, as the case may be, into the helmet ear piece sockets, and isassured ofproper hearing inasmuch as these tubes are aligned directly with the centers of the listener's ears, the projection of members 32 into the ear conchas serving'to eliminate echo efl'ecis.

As many changes could be made in the above construction and many apparently widely different embodiments of this. invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In an ear engaging head piece for sound locators, a. metallic dished oval plate arranged to overlie the ear of the user, said plate having itsconvexside positioned'outwardly and being of such .curvature as to substantially confornt to the head surroimding the ear while leaving a dead air space. between the head and the inner surface of said plate, said plate also having a central aperture,a sound conveying tube of uni-- form inner diameter throughout its length, an open-ended ear engaging tube connected with said sound conveying tube and having substantially the same inner diameter as said sound conveying tube. sa d ear engaging tube being adjustable within said aperture toward and from the ear concha to suit the user's ear and operating conditions. 1

2. An ear engaging head piece as defined in claim 1, wherein a substantially annular padding is provided adjacent the outer periphery of the inner concave surface of said dished plate-for engaging the head to shut ofl extraneous noises,

said plate inner surface being covered with a layer of sound absorbing material.

3. In a head piecefor sound locators, a pair of ear pieces each'comprising a dished plate providing'a'n inner ear receiving cavityand having .a central aperture, padded sound absorbing material secured adjacent the outer periphery of the concave inner surface of said plate to fit around the outer ear, an earengaging tube having a substantially unrestricted opening and of about and'from the ear, whereby its inner end may be adjusted-to suitably engage the ear concha OXJ moved outwardly therefrom, said plate having sound absorbing material on its inner and outer surfaces, and a separable flexible sound track to a sound receiver.

tube adapted to connect said first mentioned tube 

